JPWO2020110341A1 - Optical glass, optical elements, optical systems, interchangeable lenses and optical devices - Google Patents

Abstract

By mass%, P ₂ O ₅ component: 24.5 to 41%, Na ₂ O component: 6 to 17%, K ₂ O component: 5 to 15%, Al ₂ O ₃ component: more than 0% and 7% or less, Provided is an optical glass having a TiO ₂ component: 8 to 21%, an Nb ₂ O _{5 component: 5 to} 38%, and a partial dispersion ratio (P _{g, F) of 0.634 or less.}

Description

The present invention relates to optical glass, optical elements, optical systems, interchangeable lenses and optical devices. The present invention claims the priority of application number 2018-224548 of the Japanese patent filed on November 30, 2018, and for designated countries that are permitted to be incorporated by reference to the literature, the contents described in the application are as follows. Incorporated into this application by reference.

As an optical glass that can be used for an imaging device or the like, for example, the one described in Patent Document 1 is known. In recent years, imaging devices and the like equipped with an image sensor having a high number of pixels have been developed, and optical glasses used for these have been required to have high dispersion and low specific density.

Japanese Unexamined Patent Publication No. 2006-219365

The first aspect according to the present invention is mass%, P ₂ O ₅ component: 24.5 to 41%, Na ₂ O component: 6 to 17%, K ₂ O component: 5 to 15%, Al ₂ O. ₃ components: more than 0% and 7% or less, TiO ₂ components: 8 to 21%, Nb ₂ O _{5 components: 5 to} 38%, and a partial dispersion ratio (P _{g, F} ) of 0.634 or less. , Optical glass.

The second aspect according to the present invention is an optical element using the above-mentioned optical glass.

A third aspect of the present invention is an optical system including the above-mentioned optical element.

A fourth aspect according to the present invention is an interchangeable lens including the above-mentioned optical system.

A fifth aspect according to the present invention is an optical device including the above-mentioned optical system.

FIG. 1 is a perspective view of an image pickup apparatus including an optical element using optical glass according to the present embodiment. FIG. 2 is a front view of another example of an image pickup apparatus including an optical element using optical glass according to the present embodiment. FIG. 3 is a rear view of the image pickup apparatus of FIG. FIG. 4 is a block diagram showing an example of the configuration of the multiphoton microscope according to the present embodiment. FIG. 5 is a graph in which the optical constant values of each embodiment are plotted.

Hereinafter, embodiments according to the present invention (hereinafter, referred to as “the present embodiment”) will be described. The following embodiments are examples for explaining the present invention, and are not intended to limit the present invention to the following contents. The present invention can be appropriately modified and implemented within the scope of the gist thereof.

In the present specification, unless otherwise specified, the content of each component is all mass% (mass percentage) of the oxide-equivalent composition with respect to the total weight of the glass. The oxide-equivalent composition referred to here is the total mass of the oxide, assuming that all the oxides, composite salts, etc. used as raw materials for the glass constituents of the present embodiment are decomposed into oxides at the time of melting. Is 100% by mass, and each component contained in the glass is described.

The optical glass according to the present embodiment has P ₂ O ₅ component: 24.5 to 41%, Na ₂ O component: 6 to 17%, K ₂ O component: 5 to 15%, Al ₂ O _{3 in mass%.} Component: More than 0% and 7% or less, TiO ₂ component: 8 to 21%, Nb ₂ O _{5 component: 5 to} 38%, and a partial dispersion ratio (P _{g, F} ) of 0.634 or less. It is an optical glass.

Conventionally, a method of increasing the content of components such as _{TiO 2} and Nb ₂ O ₅ has been attempted in order to realize high dispersion. However, when these contents are increased, the transmittance tends to decrease and the specific gravity tends to increase. In this respect, the optical glass according to the present embodiment can have a low specific gravity while having a high dispersion, so that the weight of the lens can be reduced.

First, each component of the optical glass according to the present embodiment will be described.

P ₂ O ₅ is a component that forms a glass skeleton, improves devitrification resistance, and lowers the refractive index and chemical durability. If _{the content of P 2} O ₅ is too small, devitrification tends to occur easily. Further, _{if the content of P 2} O ₅ is too large, the refractive index and chemical durability tend to decrease. From this point of view, _{the content of P 2} O ₅ is 24.5% or more and 41% or less. The lower limit of this content is preferably 25% or more, more preferably 28% or more, and the upper limit of this content is preferably 40% or less, more preferably 37% or less. By _{setting the content of P 2} O ₅ in such a range, it is possible to improve the devitrification resistance and improve the chemical durability while increasing the refractive index.

Na ₂ O is a component that improves meltability and reduces chemical durability. If _{the content of Na 2} O is too small, the meltability tends to decrease. From this point of view, _{the content of Na 2} O is 6% or more and 17% or less. The lower limit of this content is preferably 7% or more, more preferably 8% or more, and the upper limit of this content is preferably 15% or less, more preferably 14% or less.

K ₂ O is a component that improves meltability and reduces chemical durability. If _{the content of K 2} O is too small, the meltability tends to decrease. From this viewpoint, the content of _{K 2} O is 15% less than 5%. The lower limit of this content is preferably 6% or more, more preferably 7% or more, and the upper limit of this content is preferably 13% or less, more preferably 12% or less.

Al ₂ O ₃ is a component that improves chemical durability and lowers devitrification resistance. If _{the content of Al 2} O ₃ is too small, the chemical durability tends to decrease. From this point of view, _{the content of Al 2} O ₃ is more than 0% and 7% or less. The lower limit of this content is preferably 0.5% or more, more preferably 1% or more, and the upper limit of this content is preferably 6.5% or less, more preferably 5% or less. Yes, more preferably 4% or less.

TiO ₂ is a component that raises the refractive index and lowers the transmittance. If _{the content of TiO 2} is high, the transmittance tends to decrease. From this point of view, _{the content of TiO 2} is 8% or more and 21% or less. The lower limit of this content is preferably 9% or more, more preferably 10% or more, and the upper limit of this content is preferably 20% or less, more preferably 19.5% or less. More preferably, it is 19% or less.

Nb ₂ O ₅ is a component that increases the refractive index and dispersibility and lowers the transmittance. When _{the content of Nb 2} O ₅ is small, the refractive index tends to be low. Further, when _{the content of Nb 2} O ₅ is large, the transmittance tends to deteriorate. From this point of view, _{the content of Nb 2} O ₅ is 5% or more and 38% or less. The lower limit of this content is preferably 6% or more, more preferably 7% or more, and the upper limit of this content is preferably 36% or less, more preferably 34% or less.

Further, the optical glass according to the present embodiment includes SiO ₂ , B ₂ O ₃ , Bi ₂ O ₃ , MgO, Li ₂ O, CaO, BaO, SrO, ZnO, ZrO ₂ , Y ₂ O ₃ , and La ₂ O _3. , Gd ₂ O ₃ , WO ₃ and Sb ₂ O ₃ may further include one or more selected from the group.

SiO ₂ is an effective component for adjusting the constant number, and from the viewpoint of further improving the devitrification resistance, the upper limit of the content thereof is preferably 3.5% or less, more preferably 2% or less. ..

B ₂ O ₃ is an effective component for adjusting the constant number, and from the viewpoint of further improving the devitrification resistance, the upper limit of the content thereof is preferably 10% or less, more preferably 7% or less. ..

Bi ₂ O ₃ is a component that is effective in improving the devitrification resistance, but is a component that deteriorates the transmittance performance. From the viewpoint of not deteriorating the transmittance performance, the upper limit of the content is preferably 5% or less, more preferably 3% or less.

MgO is an effective component for increasing the refractive index, and the upper limit of its content is preferably 2% or less from the viewpoint of further improving the devitrification resistance.

Li ₂ O is a component that improves meltability and raises the refractive index. From the viewpoint of further improving the devitrification resistance, the upper limit of the content is preferably 3.5% or less, more preferably 2% or less.

CaO is an effective component for increasing the refractive index, and from the viewpoint of further improving the devitrification resistance, the upper limit of the content thereof is preferably 9.5% or less, more preferably 8% or less. ..

BaO is an effective component for increasing the refractive index, and the upper limit thereof is preferably 9% or less, more preferably 8.5% or less, from the viewpoint of further improving the devitrification resistance.

The SrO component is an effective component for increasing the refractive index, and the upper limit thereof is preferably 1.5% or less, more preferably 0.5% or less, from the viewpoint of further improving the devitrification resistance.

ZnO is an effective component for increasing the refractive index and increasing the dispersion, and from the viewpoint of further improving the devitrification resistance, the upper limit of the content thereof is preferably 5% or less, more preferably 4% or less. Is.

ZrO ₂ is an effective component for increasing the refractive index and increasing the dispersion, and from the viewpoint of further improving the devitrification resistance, the upper limit of the content thereof is preferably 6% or less, more preferably 4%. It is as follows.

Y ₂ O ₃ is an effective component for increasing the refractive index, and from the viewpoint of further improving the devitrification resistance, the upper limit of the content thereof is preferably 1.5% or less, more preferably 0. It is 5% or less.

La ₂ O ₃ is an effective component for increasing the refractive index, and from the viewpoint of further improving the devitrification resistance, the upper limit of the content thereof is preferably 1.5% or less, more preferably 0. It is 5% or less.

Gd ₂ O ₃ is an effective component for increasing the refractive index, and from the viewpoint of further improving the devitrification resistance, the upper limit of the content thereof is preferably 2% or less, more preferably 0.5%. It is as follows.

The content of WO ₃ is an effective component for increasing the refractive index and increasing the dispersion, but since it is an expensive raw material, the upper limit of the content is preferably 3% or less, more preferably 2%. It is as follows.

Sb ₂ O ₃ is effective as a defoaming agent, but if it is contained in a certain amount or more, the transmittance performance of the glass is deteriorated. In order to improve the transmittance performance of the glass, the upper limit of the content is preferably 0.4% or less, more preferably 0.2% or less.

The optical glass according to the present embodiment is excellent in terms of raw material cost because it is possible to reduce the content of _{Ta 2} O _{5 which is an expensive raw material and further, it is possible not to contain these.}

Suitable combinations thereof include SiO ₂ component: 0 to 3.5%, B ₂ O ₃ component: 0 to 10%, Bi ₂ O ₃ component: 0 to 5%, Mg O component: 0 to 2%, Li. ₂ O component: 0 to 3.5%, CaO component: 0 to 9.5%, BaO component: 0 to 9%, SrO component: 0 to 1.5%, ZnO component: 0 to 5%, ZrO ₂ component : 0 to 6%, Y ₂ O ₃ component: 0 to 1.5%, La ₂ O ₃ component: 0 to 1.5%, Gd ₂ O ₃ component: 0 to 2%, WO ₃ component: 0 to 3 %, Sb ₂ O ₃ component: 0 to 0.4%.

In addition, the following preferred examples can be further given for the combination and ratio of each component.

The total content of P ₂ O ₅ and B ₂ O _{3 (P 2} O ₅ + B ₂ O ₃ ) is preferably 28 to 43%. The lower limit of the total sum of these contents is more preferably 30% or more, and the upper limit of the total sum of these contents is more preferably 39%. The refractive index can be increased by setting _{P 2} O ₅ + B ₂ O _{3 in such a range.}

The ratio of _B 2 _{O 3} with respect to _{P 2 O 5 (B 2 O} 3 / P 2 O 5) is preferably 0 or 0.24 or less. The lower limit of this ratio is more preferably 0.015 or more, and the upper limit of this ratio is more preferably 0.21 or less. By _{setting B 2} O ₃ / P ₂ O ₅ in such a range, the devitrification resistance can be increased and the refractive index can be increased.

The ratio of TiO ₂ with respect to _{P 2 O 5 (TiO 2 /} P 2 O 5) is preferably 0.3 to 0.7. The lower limit of this ratio is more preferably 0.4 or more, and the upper limit of this ratio is more preferably 0.6 or less. By _{setting TiO 2} / P ₂ O ₅ in such a range, the devitrification resistance can be increased and the refractive index can be increased.

The ratio of _Nb 2 _{O 5} with respect to _{P 2 O 5 (Nb 2 O} 5 / P 2 O 5) is preferably 0.1 to 1.3. The lower limit of this ratio is more preferably 0.2 or more, and the upper limit of this ratio is more preferably 1.2 or less. By _{setting Nb 2} O ₅ / P ₂ O ₅ in such a range, the refractive index can be increased.

The total content of Li ₂ O, Na ₂ O and K _{2 O (Li 2} O + Na ₂ O + K ₂ O) is preferably 14% or more and 25% or less. The lower limit of the total sum of these contents is more preferably 15% or more, and the upper limit of the total sum of these contents is more preferably 23% or less. By _{setting Li 2} O + Na ₂ O + K ₂ O in such a range, the meltability can be improved without lowering the chemical durability.

If necessary, add an appropriate amount of known clarifying agents, coloring agents, defoaming agents, fluorine compounds, and other components to the glass composition for the purpose of clarification, coloring, decolorization, fine adjustment of optical constants, and the like. Can be done. Further, not limited to the above-mentioned components, other components may be added as long as the effect of the optical glass of the present embodiment can be obtained.

The method for producing the optical glass according to the present embodiment is not particularly limited, and a known method can be adopted. Further, as the manufacturing conditions, official conditions can be appropriately selected. As one of the preferable examples, one selected from oxides, hydroxides, phosphoric acid compounds (phosphate, orthophosphoric acid, etc.), carbonates, nitrates, etc. corresponding to the above-mentioned raw materials is used as a glass raw material. Examples thereof include a step of selecting, mixing the mixture, melting the mixture at a temperature of 1100 to 1400 ° C., stirring and homogenizing the mixture, and then cooling and molding the mixture.

More specifically, raw materials such as oxides, carbonates, nitrates, and sulfates are prepared so as to have a target composition, preferably 1100 to 1400 ° C., more preferably 1100 to 1300 ° C., still more preferably 1100 to 1250. It is possible to adopt a manufacturing method in which the product is melted at ° C., homogenized by stirring, foam is cut off, and then cast into a mold. The optical glass thus obtained can be reheat-pressed or the like to be processed into a desired shape and polished to obtain a desired optical glass or optical element.

Since the composition of the optical glass according to the present embodiment is easy to melt, it is easy to make the stirring uniform, and the production efficiency is excellent. That is, when 50 g of the raw material of the optical glass is heated at a temperature of 1100 to 1250 ° C., the time until the raw material melts is preferably less than 15 minutes, more preferably 13 minutes or less, still more preferably. It is less than 10 minutes. The "time until melting" here is the time from the start of heating and holding the raw materials required for the construction of the optical glass until these raw materials are melted and cannot be visually confirmed near the liquid surface. say.

Since the glass raw material melts in a short time as described above in the temperature range of 1100 to 1250 ° C., it is possible to prevent the remaining glass raw material from being mixed into the glass. Further, if the remaining glass raw material is forcibly melted and heated at a high temperature or held for a long time, it may cause a decrease in glass production efficiency and a deterioration in transmittance. Such a problem does not occur.

Further, it is preferable to use a high-purity product having a low content of impurities as the raw material. A high-purity product contains 99.85% by mass or more of the component. The use of high-purity products tends to increase the internal transmittance of optical glass as a result of reducing the amount of impurities.

Next, various physical property values of the optical glass of the present embodiment will be described.

The optical glass according to this embodiment has a partial dispersion ratio (P _{g, F} ) of 0.634 or less. Further, since the optical glass according to the present embodiment _{realizes a large partial dispersion ratio (P g, F} ), it is effective for correcting the aberration of the lens. _{From this point of view, the lower limit of the partial dispersion ratio (P g, F} ) of the optical glass according to the present embodiment is preferably 0.6 or more, more preferably 0.610 or more. The upper limit of the partial dispersion ratio (P _{g, F} ) is more preferably 0.632 or less.

From the viewpoint of thinning the lens, it is desirable that the optical glass according to the present embodiment has a high refractive index (high refractive index ( _nd)). However, in general, the higher the refractive index, the higher the specific gravity tends to be. Given the above circumstances, the refractive index to the d-line in the optical glass according to the present embodiment _(n d), is preferably in the range of 1.66 to 1.81. The lower limit of the refractive index ( _nd ) is more preferably 1.67 or more, and _{the upper limit of the refractive index (nd} ) is more preferably 1.80 or less.

_{The Abbe number (ν d} ) of the optical glass according to this embodiment is preferably in the range of 22 to 32. The lower limit of the Abbe number (ν _d ) is more preferably 23 or more, further preferably 24 or more, and _{the upper limit of the Abbe number (ν d} ) is more preferably 29 or less, still more preferably 28. It is as follows.

Then, the optical glass according to the present embodiment, the preferred combination of refractive index _{(n d)} and Abbe number ([nu _d) is a refractive index _{(n d)} is 1.66 to 1.81, and an Abbe number (Ν _d ) is 22 to 32. The optical glass according to the present embodiment having such properties can be used as a convex lens in a concave lens group in combination with other optical glasses, for example, to design an optical system in which chromatic aberration and other aberrations are satisfactorily corrected. be.

From the viewpoint of reducing the weight of the lens, it is desirable that the optical glass according to the present embodiment has a low specific gravity. However, in general, the lower the specific gravity, the lower the refractive index tends to be. Based on such circumstances, the preferable specific gravity of the optical glass according to the present embodiment is in the range of 2.8 to 3.4 with 2.8 as the lower limit and 3.4 as the upper limit.

The value (ΔP _{g, F} ) indicating the anomalous dispersibility is preferably 0.0190 to 0.0320. This upper limit is more preferably 0.0315 or less, further preferably 0.0310 or less, and this lower limit is more preferably 0.0200 or more, still more preferably 0.0210 or more. ΔP _{g and F} are indexes of anomalous dispersibility and can be obtained according to the method described in Examples described later.

From the above viewpoint, the optical glass according to the present embodiment has low raw material cost, low specific density, and high dispersion ( _{small Abbe number (ν d} )). In addition, the values (ΔP _{g, F} ) indicating the anomalous dispersibility and the partial dispersion ratios P _{g, F} can also be increased. The optical glass according to this embodiment is suitable as an optical element such as a lens provided in an optical device such as a camera or a microscope. Such optical elements include mirrors, lenses, prisms, filters and the like. Examples of the optical system including these optical elements include an objective lens, a condenser lens, an imaging lens, an interchangeable lens for a camera, and the like. Then, these can be used for an imaging device such as an interchangeable lens camera and a non-interchangeable lens camera, and a microscope such as a multiphoton microscope. The optical device is not limited to the above-mentioned imaging device and microscope, but also includes a video camera, a teleconverter, a telescope, binoculars, a monocular, a laser range finder, a projector, and the like. An example of these will be described below.

<Imaging device>
FIG. 1 is a perspective view of an image pickup apparatus including an optical element using optical glass according to the present embodiment.

The image pickup apparatus 1 is a so-called digital single-lens reflex camera (interchangeable lens camera), and the photographing lens 103 (optical system) includes an optical element using the optical glass according to the present embodiment as a base material. The lens barrel 102 is detachably attached to the lens mount (not shown) of the camera body 101. Then, the light passing through the lens 103 of the lens barrel 102 is imaged on the sensor chip (solid-state image sensor) 104 of the multi-chip module 106 arranged on the back side of the camera body 101. The sensor chip 104 is a bare chip such as a so-called CMOS image sensor, and the multi-chip module 106 is, for example, a COG (Chip On Glass) type module in which the sensor chip 104 is bare-chip mounted on a glass substrate 105.

FIG. 2 is a front view of another example of an image pickup apparatus including an optical element using optical glass according to the present embodiment, and FIG. 3 is a rear view of the image pickup apparatus of FIG.

This imaging device CAM is a so-called digital still camera (non-interchangeable lens camera), and the photographing lens WL (optical system) is provided with an optical element using the optical glass according to the present embodiment as a base material.

When the power button (not shown) is pressed, the shutter (not shown) of the photographing lens WL is released, and the light from the subject (object) is collected by the photographing lens WL and arranged on the image plane. An image is formed on the image pickup element. The subject image formed on the image pickup device is displayed on the liquid crystal monitor LM arranged behind the image pickup apparatus CAM. After deciding the composition of the subject image while looking at the liquid crystal monitor LM, the photographer presses the release button B1 to capture the subject image with the image sensor, and records and saves the subject image in a memory (not shown).

The image pickup device CAM is provided with an auxiliary light emitting unit EF that emits auxiliary light when the subject is dark, a function button B2 used for setting various conditions of the image pickup device CAM, and the like.

The optical system used in such a digital camera or the like is required to have higher resolution, lighter weight, and smaller size. In order to realize these, it is effective to use glass having a high refractive index for the optical system. In particular, there is a high demand for glass having a high refractive index but a lower specific gravity (S _{g) and high press moldability.} From this point of view, the optical glass according to the present embodiment is suitable as a member of such an optical device. The optical device applicable to this embodiment is not limited to the above-mentioned imaging device, and examples thereof include a projector and the like. The optical element is not limited to a lens, and examples thereof include a prism and the like.

<Multiphoton microscope>
FIG. 4 is a block diagram showing an example of the configuration of a multiphoton microscope 2 including an optical element using the optical glass according to the present embodiment.

The multiphoton microscope 2 includes an objective lens 206, a condenser lens 208, and an imaging lens 210. At least one of the objective lens 206, the condenser lens 208, and the imaging lens 210 is provided with an optical element using the optical glass according to the present embodiment as a base material. Hereinafter, the optical system of the multiphoton microscope 2 will be mainly described.

The pulse laser device 201 emits ultrashort pulsed light having, for example, a near infrared wavelength (about 1000 nm) and a pulse width in femtosecond units (for example, 100 femtoseconds). The ultrashort pulsed light immediately after being emitted from the pulse laser device 201 is generally linearly polarized light polarized in a predetermined direction.

The pulse dividing device 202 divides the ultrashort pulsed light and emits the ultrashort pulsed light at a high repetition frequency.

The beam adjusting unit 203 has a function of adjusting the beam diameter of the ultrashort pulsed light incident from the pulse dividing device 202 according to the pupil diameter of the objective lens 206, and the wavelength and ultrashort of the multiphoton excitation light emitted from the sample S. A function to adjust the focusing and divergence angle of ultrashort pulsed light to correct axial chromatic aberration (focus difference) with the wavelength of pulsed light, and a group while the pulse width of ultrashort pulsed light passes through the optical system. It has a pre-charp function (group velocity dispersion compensation function) that gives the ultra-short pulsed light the opposite group velocity dispersion in order to correct the spread due to the velocity dispersion.

The repetition frequency of the ultrashort pulsed light emitted from the pulse laser device 201 is increased by the pulse dividing device 202, and the above-mentioned adjustment is performed by the beam adjusting unit 203. Then, the ultrashort pulsed light emitted from the beam adjusting unit 203 is reflected by the dichroic mirror 204 in the direction of the dichroic mirror, passes through the dichroic mirror 205, is collected by the objective lens 206, and is irradiated to the sample S. At this time, by using a scanning means (not shown), the ultrashort pulsed light may be scanned on the observation surface of the sample S.

For example, when observing the sample S by fluorescence, the fluorescent dye in which the sample S is stained is multiphoton excited in the irradiated region of the ultrashort pulsed light of the sample S and its vicinity, and the ultrashort wavelength is an infrared wavelength. Fluorescence (hereinafter referred to as "observation light") having a shorter wavelength than pulsed light is emitted.

The observation light emitted from the sample S in the direction of the objective lens 206 is collimated by the objective lens 206 and reflected by the dichroic mirror 205 or transmitted through the dichroic mirror 205 depending on the wavelength thereof.

The observation light reflected by the dichroic mirror 205 is incident on the fluorescence detection unit 207. The fluorescence detection unit 207 is composed of, for example, a barrier filter, a PMT (photomultiplier tube), etc., receives the observation light reflected by the dichroic mirror 205, and outputs an electric signal according to the amount of the light. .. Further, the fluorescence detection unit 207 detects the observation light over the observation surface of the sample S as the ultrashort pulse light is scanned on the observation surface of the sample S.

On the other hand, the observation light transmitted through the dichroic mirror 205 is descanned by scanning means (not shown), transmitted through the dichroic mirror 204, collected by the condenser lens 208, and placed at a position substantially conjugate with the focal position of the objective lens 206. It passes through the provided pinhole 209, passes through the imaging lens 210, and is incident on the fluorescence detection unit 211.

The fluorescence detection unit 211 is composed of, for example, a barrier filter, a PMT, or the like, receives the observation light imaged on the light receiving surface of the fluorescence detection unit 211 by the imaging lens 210, and outputs an electric signal according to the amount of the light. Further, the fluorescence detection unit 211 detects the observation light over the observation surface of the sample S as the ultrashort pulse light is scanned on the observation surface of the sample S.

By removing the dichroic mirror 205 from the optical path, the fluorescence detection unit 211 may detect all the observation light emitted from the sample S in the direction of the objective lens 206.

Further, the observation light emitted from the sample S in the direction opposite to that of the objective lens 206 is reflected by the dichroic mirror 212 and incident on the fluorescence detection unit 213. The fluorescence detection unit 213 is composed of, for example, a barrier filter, a PMT, or the like, receives the observation light reflected by the dichroic mirror 212, and outputs an electric signal according to the amount of the light. Further, the fluorescence detection unit 213 detects the observation light over the observation surface of the sample S as the ultrashort pulse light is scanned on the observation surface of the sample S.

The electric signals output from the fluorescence detection units 207, 211, and 213 are input to, for example, a computer (not shown), and the computer generates an observation image based on the input electric signals, and the generated observation. Images can be displayed and observation image data can be stored.

Next, the following Examples and Comparative Examples will be described, but the present invention is not limited to the following Examples.

<Making optical glass>
The optical glass according to each Example and Comparative Example was produced by the following procedure. First, a glass raw material selected from oxides, hydroxides, phosphoric acid compounds (phosphate, orthophosphoric acid, etc.), carbonates, nitrates, etc. is weighed so as to have the composition (mass%) shown in each table. bottom. Next, the weighed raw materials were mixed and put into a platinum crucible, melted at a temperature of 1100 to 1300 ° C. for about 70 minutes, and stirred and homogenized. After defoaming, the temperature was lowered to an appropriate temperature, cast into a mold, slowly cooled, and molded to obtain each sample.

1. 1. Refractive index ( _nd ) and Abbe number (ν _d )
The refractive index ( _nd ) and Abbe number (ν _d ) of each sample were measured and calculated using a refractive index measuring device (manufactured by Shimadzu Device Manufacturing Co., Ltd .: KPR-2000). n _d represents the refractive index of the glass for the light of the d-line (wavelength 587.562 nm). ν _d was obtained from the following equation (1). n _C and n _F indicate the refractive indexes of the glass with respect to the C line (wavelength 656.273 nm) and the F line (wavelength 486.133 nm), respectively.

ν _d = (n _d -1) / (n _F −n _C ) ・ ・ ・ (1)

2. Partial dispersion ratio (P _{g, F} )
The partial dispersion ratio (P _{g, F} ) of each sample indicates the ratio of the partial dispersion ( _{ng −} n _F ) to the main dispersion (n _{F −} n _C ), and was calculated from the following formula (2). _ng indicates the refractive index of the glass with respect to the g line (wavelength 435.835 nm).

P _{g, F} = ( _ng −n _F ) / (n _F −n _C ) ・ ・ ・ (2)

3. 3. Values indicating anomalous dispersibility (ΔP _{g, F} )
_{The values (ΔP g, F} ) indicating the anomalous dispersibility of each sample were determined according to the method shown below.

(1) Preparation of reference line First, as normal partially dispersed glass, two glasses "F2" and "K7" having the _{Abbe number (ν d} ) and partial dispersion ratio (P _{g, F) shown below are used as reference materials.} Using. Then, for each glass, the horizontal axis is the Abbe number (ν _d ), the vertical axis is the partial dispersion ratio (P _{g, F} ), and the straight line connecting the two points corresponding to the two reference materials is used as the reference line. ..

Characteristics of glass "F2": ν _d = 36.33, P _{g, F} = 0.5834
Characteristics of glass "K7": ν _d = 60.47, P _{g, F} = 0.5429

(2) _{Calculation of ΔP g, F} Next, on the graph with the Abbe number (ν _d ) on the horizontal axis and the partial dispersion ratio (P _{g, F} ) on the vertical axis, the values corresponding to the optical glass of each example are shown. Plot (see FIG. 5), and the difference between the point on the reference line corresponding to _{the Abbe number (ν d ) of the above-mentioned glass type and the value (P g, F} ) on the vertical axis thereof is a value indicating anomalous dispersibility (see FIG. 5). Calculated as ΔP _{g, F).} When the partial dispersion ratio (P _{g, F} ) is above the reference line, ΔP _{g, F} has a positive value, and the partial dispersion ratio (P _{g, F} ) is below the reference line. , ΔP _{g, F} have negative values.

4. Relative density (S _g )
The specific gravity (S _g ) of each sample was determined from the mass ratio of the same volume of pure water at 4 ° C.

5. Melting time of glass raw material The melting time of glass raw material is the time from when 50 g of glass raw material is mixed well and put into a platinum crucible and heating and holding is started at a temperature of 1100 to 1250 ° C. until the glass raw material is melted. means. In this example, it was determined that the glass raw material was melted because the undissolved residue of the glass raw material could not be visually confirmed on the glass liquid surface in the platinum crucible.

Each table shows the composition of each Example and each Comparative Example and their physical property values. Unless otherwise specified, the content of each component is based on mass%.

FIG. 5 is a graph in which the optical constant values of each embodiment are plotted.

It was confirmed that the optical glass of this example had a low specific gravity while having a high dispersion and had a large ΔP _{g, F} and P _{g, F values.} In addition, it was confirmed that the production efficiency was excellent because the melting time of the glass raw material at the time of glass production was short. In Comparative Examples 1 to 4, it was impossible to measure various physical property values due to devitrification.

1 ... Imaging device, 101 ... Camera body, 102 ... Lens barrel, 103 ... Lens, 104 ... Sensor chip, 105 ... Glass substrate, 106 ... Multi-chip module, 2 ... Multiphoton microscope, 201 ... Pulse laser device, 202 ... Pulse divider, 203 ... Beam adjustment unit, 204, 205, 212 ... Dycroic mirror, 206 ... Objective lens, 207, 211,213 ... Fluorescence detector, 208 ... Condensing lens, 209 ... Pinhole, 210 ... Imaging lens, S ... Sample, CAM ... Imaging device, WL ...・ ・ Shooting lens, EF ・ ・ ・ Auxiliary light emitting part, LM ・ ・ ・ LCD monitor, B1 ・ ・ ・ Release button, B2 ・ ・ ・ Function button

The first aspect according to the present invention is mass%, P ₂ O ₅ content : 24.5 to 41%, Na ₂ O content : 6 to 17%, K ₂ O content : 5 to 15%, Al ₂ O ₃ content : more than 0% and 7% or less, TiO ₂ content : 8 to 21%, Nb ₂ O 5 content _{: 5 to} 38%, and partial dispersion ratio (P _{g, F} ). It is an optical glass having a ratio of 0.634 or less.

Claims (15)

By mass%
P ₂ O ₅ component: 24.5-41%,
Na ₂ O component: 6 to 17%,
K ₂ O ingredients: 5-15%,
Al ₂ O ₃ component: more than 0% and less than 7%,
TiO ₂ component: 8-21%,
Nb ₂ O _{5 component: 5 to} 38% and
The partial dispersion ratio (P _{g, F} ) is 0.634 or less.
Optical glass. By mass%
SiO ₂ component: 0-3.5%,
B ₂ O ₃ component: 0-10%,
Bi ₂ O ₃ component: 0-5%,
MgO component: 0-2%,
Li ₂ O component: 0-3.5%,
CaO component: 0-9.5%,
BaO component: 0-9%,
SrO component: 0-1.5%,
ZnO component: 0-5%,
ZrO ₂ component: 0-6%,
Y ₂ O ₃ component: 0-1.5%,
La ₂ O ₃ component: 0-1.5%,
Gd ₂ O ₃ component: 0-2%,
WO ₃ component: 0-3% _,
Sb ₂ O ₃ component: 0-0.4%,
The optical glass according to claim 1. By mass%
Total content of P ₂ O ₅ component and B ₂ O ₃ component: 28-43%,
The optical glass according to any one of claims 1 or 2. On a mass% basis,
The ratio of the B ₂ O ₃ component to the P ₂ O _{5 component (B 2} O ₃ / P ₂ O ₅ ): 0 to 0.24.
The optical glass according to any one of claims 1 to 3. On a mass% basis,
The ratio of the TiO ₂ component to the P ₂ O _{5 component (TiO 2} / P ₂ O ₅ ): 0.3 to 0.7.
The optical glass according to any one of claims 1 to 4. On a mass% basis,
P _{2 O Nb 2} O ₅ component the ratio of the ₅ component _{(Nb 2 O 5 / P 2} O 5): is 0.1 to 1.3,
The optical glass according to any one of claims 1 to 5. By mass%
Total content of Li ₂ O component, Na ₂ O component and K ₂ O component: 14 to 25% or less,
The optical glass according to any one of claims 1 to 6. the refractive index at the d-line _{(n d)} is in the range of 1.66 to 1.81, and,
The Abbe number (ν _d ) is in the range of 22 to 32,
The optical glass according to any one of claims 1 to 7. The specific density (S _g ) is 2.8 to 3.4,
The optical glass according to any one of claims 1 to 8. ΔP _{g, F} is 0.0190 to 0.0320,
The optical glass according to any one of claims 1 to 9. The optical glass according to any one of claims 1 to 10, wherein when 50 g of the raw material of the optical glass is heated at a temperature of 1100 to 1250 ° C., the time until the raw material melts is less than 15 minutes. .. An optical element using the optical glass according to any one of claims 1 to 11. An optical system including the optical element according to claim 12. An interchangeable lens comprising the optical system according to claim 13. An optical device comprising the optical system according to claim 13.

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